FIELD OF THE INVENTION

The present disclosure relates to a coupler for coupling an implement to the arm of an excavator, digger, or other earth moving machine or vehicle. In particular, the coupler is a hydraulic coupler with safety features to prevent decoupling in the event of a hydraulic failure or due to the incomplete coupling of an implement during the coupling process.

BACKGROUND

Couplers, also commonly called 'hitches', are used to removably connect implements such as an excavation bucket or other earth moving implement, to an arm of a machine such as an excavator, digger, or backhoe. These couplers are typically mounted to the free end of the arm and configured to engage a pair of parallel pins ordinarily provided on earth moving implements for connection of the implement to the arm.

Modern couplers are operated using a hydraulic actuator. This enables implements to be changed out from the end of the excavator arm quickly and remotely by the vehicle operator, releasing one implement from the coupler, and engaging the pins of another implement. During use, implements are held securely by the coupler under hydraulic pressure. However, in the event of a failure resulting from a loss of hydraulic pressure or a failure to correctly engage both pins, there is a risk of the implement coming loose or falling from the arm. A loose or dropped implement is a safety hazard and can result in serious injury.

To mitigate the risk of hydraulic failure, hydraulic couplers commonly have one or more safety lock features to ensure one or both of the pins on the implement remain engaged with the coupler in the case of a hydraulic failure resulting in a loss of hydraulic pressure. In some existing couplers, a spring-loaded latch is used as a safety latch on at least one of the coupler jaws. However, these spring-loaded safety latches may fail under specific loading conditions. One such condition is when there is a loss of hydraulic pressure and the coupler is in or is moved to a vertical or near-vertical orientation such that the pins of the implement are vertically aligned. In this vertical orientation, the hydraulic failure results in the pins and the upper jaw dropping slightly under gravity so substantially all of the vertical loading from the implement and the implement load is transferred to the spring-loaded latch. This transfer of force to the latch may damage or cause failure of the latch which is not sufficiently robust to support that magnitude of load, thereby risking the implement being dangerously released from the coupler.

Hazardous situations can also occur if an operator unknowingly does not correctly couple the coupler to the pins of the implement. The process of coupling the coupler with an implement typically involves engaging a front fixed jaw of the coupler to a first pin of the implement, including engaging a front safety latch, then curling the implement under the excavator arm and moving a rear jaw of the coupler into engagement with the second pin. However, an operator often cannot see the engagement of the rear jaw with the second pin so may not notice if the rear jaw hasn't correctly engaged the second pin. Therefore, there is a risk an operator will attempt to move the excavator arm and attached coupler with the implement only partly engaged.

If the excavator arm is moved in this condition, the implement may swing about and hang from the first pin as the coupler is raised. The momentum of the swinging implement may push the first pin hard against the front latch, again causing the latch to bear a majority of the load of the implement. Further, there have been incidents where, as the implement pivots around the first pin, the rotating pin in contact with the latch applies a torque to the latch to pivot the latch out of engagement. This frees the first pin from the jaw and causes the implement to fall dangerously.

It is an object of at least preferred embodiments of the present invention to address one or more of the above-mentioned shortcomings and/or to at least provide the public with a useful alternative.

In this specification where reference has been made to patent specifications, other external documents, or other sources of information, this is generally to provide a context for discussing features of the invention. Unless specifically stated otherwise, reference to such external documents or sources of information is not to be construed as an admission that such documents or such sources of information, in any jurisdiction, are prior art or form part of the common general knowledge in the art.

SUMMARY OF THE INVENTION

In a first aspect, the invention broadly relates to a coupler for coupling an implement having first and second spaced apart parallel pins, to the arm of a vehicle or machine. The coupler comprises a body for attaching to the vehicle or machine arm, a front first jaw fixed relative to the body, a pivotable locking member, a movable rear second jaw, and an actuator. The front first jaw defines an opening and a first seat for receiving the first implement pin, and comprises a pronounced lip forward of the first seat, the lip protruding in a direction generally towards the body. The locking member is pivotable relative to the first jaw about a pivot that is positioned forward of the lip of the first jaw. The locking member pivots between a locking position in which a portion of the locking member protrudes into the opening of the first jaw, and an unlocked position in which the locking member is substantially or wholly retracted from the opening of the first jaw. The movable rear second jaw faces away from the first jaw, defining an opening and a second seat for receiving the second implement pin. The second jaw comprises an extension surface adjacent to the jaw opening and rear of the second seat. The actuator is operable to selectively move the second jaw towards and away from the first jaw along a movement axis. The first jaw including the lip defines an entry direction of the first pin into the seat of the first jaw that is not parallel to the movement axis.

In an embodiment, the second jaw is movable between an extended position with the second jaw distal to the first jaw and a contracted position with the second jaw proximal to the first jaw.

In an embodiment, the movable second jaw is biased in a position away from the first jaw.

In an embodiment, the actuator is a hydraulic cylinder, and wherein a biasing member is arranged to bias the cylinder towards an extended position. The biasing member may comprise a die spring, for example, positioned within a rod of the cylinder. Alternatively, the biasing member may comprise an external compression spring.

In an alternative embodiment, the actuator may comprise a mechanical screw and thread mechanism.

The protruding lip of the first jaw may comprise a rear surface oriented at an angle of between about 20 degrees and about 40 degrees relative to the movement axis, preferably between about 25 degrees and about 35 degrees, most preferably about 30 degrees.

In an embodiment, the lip of the first jaw is shaped such that, in a vertical orientation of the coupler with the second jaw above the first jaw, weight forces from an implement secured in the coupler are at least partly supported by the lip.

In an embodiment, engagement of the first jaw with an implement pin requires a change in direction of the motion of the first jaw or said implement pin, to clear the lip of the first jaw. During at least one part of the motion, engagement of the first jaw with an implement pin may require the first jaw or said implement pin to move such that the movement vector comprises a component that is perpendicular to the movement axis of the movable member.

In an embodiment, the locking member is shaped such that, in a vertical orientation of the coupler with the second jaw above the first jaw and the locking member in a locking position, weight forces from an implement secured in the coupler are at least partly supported by the locking member. In a vertical orientation of the coupler with the second jaw above the first jaw and the locking member in a locking position, reaction force vectors provided by the locking member to support the first implement may extend through the locking member pivot. In an embodiment, in a vertical orientation of the coupler with the second jaw above the first jaw and the locking member in a locking position, at least a major portion of weight forces from an implement secured in the coupler are supported by the locking member and the lip of the first jaw support. For example, the locking member and the lip may together support substantially all of the weight force of the implement load. In alternative embodiments, the locking member and the lip may together support a majority of the weight force of the implement load, for example more than about 70% of the weight force of the implement load. The load supported by the locking member and the lip may be evenly or unevenly distributed between the locking member and the lip. For example, the lip may support about 50% and the locking member may support about 50%. Alternatively, the load proportions may be distributed, 30-70, 40-60, 60-40, 70-30, or any other such distribution.

In an embodiment, the locking member comprises a locking surface for contacting the first implement pin at a contact point, the contact point being substantially colinear with a centre of said pin and a pivot axis of the locking member. the locking surface at the contact point is substantially perpendicular with an axis running between the centre of said pin and the locking member pivot axis.

In an embodiment, the locking surface is substantially flat.

In an embodiment, wherein the locking member is biased towards the locking position. A leaf spring may be provided and arranged to bias the locking member towards the locking position. For example, a first end of the leaf spring may be anchored to the body, a second end of the leaf spring may be anchored to the locking member, with the leaf spring comprising a bent intermediate portion adjacent the locking member pin. Alternatively, a torsion spring or a coil spring may be provided to bias the locking member towards the locking position.

In an embodiment, the locking member comprises a cam surface; and wherein the movable jaw is provided on a movable member, the movable member being configured to engage the cam surface and thereby retract the locking member from its locking position as the movable jaw moves towards the first jaw.

In an embodiment, the extension surface of the second jaw is configured such that, in the event of a failure of the actuator resulting in slight movement of the second jaw towards the first jaw, the extension surface prevents rotation of an implement attached to the coupler by retaining the second pin in the second jaw. In an embodiment, the extension surface of the second jaw is substantially flat and/or is substantially parallel to the movement axis.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more said parts, elements or features. Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually described.

The term 'comprising' as used in this specification and claims means 'consisting at least in part of'. When interpreting statements in this specification and claims that include the term 'comprising', other features besides those prefaced by this term can also be present. Related terms such as 'comprise' and 'comprised' are to be interpreted in a similar manner.

It is intended that reference to a range of numbers disclosed herein (for example, 1 to 10) also incorporates reference to all rational numbers within that range and any range of rational numbers within that range (for example, 1 to 6, 1.5 to 5.5 and 3.1 to 10). Therefore, all subranges of all ranges expressly disclosed herein are hereby expressly disclosed.

As used herein the term '(s)' following a noun means the plural and/or singular form of that noun. As used herein the term 'and/or' means 'and' or 'or', or where the context allows, both.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will now be described by way of example only and with reference to the accompanying drawings in which:

Figure 1 shows a front underside perspective view of a coupler according to a first exemplary embodiment;

Figure 2 shows a rear underside perspective view of the coupler of figure 1;

Figure 3 is a side elevation of the coupler of figures 1 and 2, with the coupler in a locked configuration, engaged with a pair of implement pins;

Figure 4 is a side perspective view of the coupler of figures 1 to 3, with the fixed jaw component hidden to reveal the movable member, actuator, and front locking member;

Figure 5A is a side view corresponding to the view of Figure 4, with the second jaw in a position to engage an implement pin;

Figure 5B is a side view corresponding to the view of Figure 4, with the second jaw in a position to release the first implement pin;

Figure 6 is a side section view of the coupler of Figures 1 to 5B, taken through a midplane of the coupler;

Figure 7 is an exploded perspective view of the coupler of figures 1 to 6; Figures 8A to 8E are side elevation views showing the steps to couple the coupler attached to the end of an arm of an excavator, to parallel pins on an excavator bucket, where Figure 8A shows the coupler in an unlocked configuration, ready to couple to the implement, Figure 8B shows the coupler receiving a first one of the pins, Figure 8C shows the coupler pivoted around and aligned with the second pin, ready to receive the second pin, Figure 8D shows the front locking member deployed to lock the first pin in the first jaw with the second jaw moving towards the second pin, and Figure 8E shows the coupler engaged with the second pin and in a locked configuration such that both pins are locked to the coupler, with the excavator arm lifting the coupled bucket;

Figure 9A is a side section view showing the front locking member deployed to lock the first pin in the first jaw with the second jaw moved towards the second pin in a misaligned state and prevented from engaging the pin;

Figure 9B illustrates a first stage of movement of the implement upon movement of the coupler from the state shown in Figure 9A;

Figure 9C illustrates a second stage of movement of the implement upon further movement of the coupler from the state shown in Figure 9B;

Figure 9D illustrates a further stage of movement of the implement upon further movement of the coupler from the state shown in Figure 9C;

Figure 10A is a side view showing the coupler coupled to an implement in a vertical orientation, illustrating reaction forces;

Figure 10B is a side view showing the coupler coupled to an implement in a vertical orientation after a hydraulic failure, illustrating the reaction forces;

Figures 11A to HE are side section detail views of the front jaw and locking member of an alternative embodiment coupler, where Figure HA shows a pin seated in the first jaw and the movement path for moving the pin into and out of the jaw; Figure 11B is similar to Figure HA but showing the locking member; Figure 11C shows the first pin moved into contact with the locking member; Figures 11C and HD show the locking member moving into the retracted position.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT

Figures 1 to 10b show an exemplary coupler 1 according to one embodiment of the invention. The coupler 1 is suitable for coupling an implement having first and second spaced apart parallel pins 2a, 2b, to the arm of a vehicle or machine. Transverse parallel pins 2a, 2b are commonly provided as a standard feature on implements such as excavation buckets, ripping attachments, sieve buckets, clamp, wide buckets, hydraulic hammers, screw augers, etc. to assist with attachment of the implement to an arm/boom on a vehicle or other machine.

An arrow marked "F" has been inserted into the figures where appropriate to indicate a forward direction of the coupler 1. The front F of the coupler 1 in the embodiment shown is the side corresponding with the front of the implement (the open side of the excavator bucket). The absolute orientation of the coupler 1 will change during the course of its use as the arm to which it is mounted moves. Accordingly the terms forward, rearward, left side, and right side (or similar) should be construed with reference to the forward direction F of the coupler, not necessarily with reference to the orientation shown in a given figure, the use of these terms is for ease of explanation and is not intended to be limiting.

The coupler 1 has a body 3, a first jaw 5 that is fixed relative to the body 3, a movable second jaw 7 that is movable relative to the body 3, and an actuator 9 operable to selectively move the second jaw 7 towards and away from the first jaw 5. The body 3 is configured for attachment to a vehicle or machine arm, for example, via attachment features. The coupler 1 is configured to hold a first pin 2a in the first jaw 5 and a second parallel pin 2b in the second jaw in a position such that the centres of the first and second pins are coincident with a virtual pin axis VPA (see Figures 3 and 6).

In the embodiment shown, the body 3 comprises two spaced apart parallel plates 4, to receive an end of the arm or links from the arm between the plates 4. The plates 4 include mounting apertures 6 for bolting the coupler body 3 to the arm or arm links, however other attachment methods are possible. A lifting lug 8 (Figure 2) is provided, preferably at the aft of the coupler body 3, to facilitate the lifting of various items on the worksite, for example using a chain placed through the aperture in the lug 8.

The first jaw 5 is hook-shaped, defining an opening 11 to the front F of the coupler 1. An inner surface of the first jaw 5 provides a seat 13 for receiving the first implement pin 2a. The first and second implement pins 2a, 2b are substantially cylindrical, accordingly, the surface of the first jaw 5 providing the seat 13 for the implement pin 2a is concave with a curvature that substantially corresponds to that of the pin 2a.

In the embodiment shown, the first jaw 5 is provided by two parallel hooks formed from two spaced apart side plates 15 that are fixed relative to, or integral with, the body 3 of the coupler 1. A web 16 bridges between the hooks of the two plates 15 to provide stiffness. In some embodiments, the web 16 may form at least part of the seat for the implement pin 2a as well as providing stiffness to the first jaw 5.

Referring to Figure 3, the first jaw 5 includes a raised, pronounced lip 17 forward of the pin seat 13. The lip 17 protrudes upwards, into the opening 11 of the first jaw 5, reducing the size of the opening adjacent to the lip 17 and defining a recess rear of the lip 17, which forms the seat 13. In the embodiment shown, the lip 17 is formed by the portion of the first jaw hook that curves around on itself, that is, referring to Figure 3, a portion of the hook forward of the first pin 2a vertical centre line VCa, with the rear surface of the lip 17 being contiguous with the seating surface and having forming a smooth transition between the lip 17 and the seat 13. The rear surface of the lip 17 may be curved or substantially linear. For example, in some embodiments, the lip 17 may instead be a discrete and/or abrupt projection. The lip 17 preferably extends across the width of the coupler 1 between the two side plates 15, with a portion of the lip being formed by the web 16, but alternatively a lip may be provided only by each jaw side plate 15.

The pronounced lip has a height LH, measured from the lowest point of the seat 13 to the tip of the lip 17 in a direction towards the pin axis VPA, that is at least 8% of the diameter of the pin 2a that the coupler is configured for use with (about 20% of the radius of curvature of the seat 13). More preferably the lip 17 has a height of between about 10% and about 25% of the diameter of the pin 2a (between about 20% and about 50% of the radius of curvature of the seat 13). In the embodiment shown, the lip 17 has a height LH of about 12.5% of the diameter of the pin 2a (about a 25% of the radius of curvature of the seat 13)

In the embodiment shown, the tip of the lip 17 is positioned forward of the seat 13 at a point that is slightly rear of the front most point on the first pin 2a when the pin is seated in the front jaw. For example, the tip of the lip 17 is a distance rear of the front most point on the first pin 2a that is less than about 10% of the pin diameter. In alternative embodiments and as illustrated in Figures 11A, 11B, and 11C, the tip of the lip 17 may be slightly forward of the front most point on the first pin 2a. For example, the tip of the lip 17 may forward of the front most point on the pin 2a by a distance that is less than about 10% of the pin diameter.

The lip 17 is pronounced in that it requires the implement pin 2a to navigate a non-linear entry and exit path relative to the coupler 1 on its way through the opening 11 into and out of its fully seated position on the seat 13. The direction of movement of the implement pin 2a past the lip 17 (or movement of the lip 17 past the implement pin 2a), is not parallel with virtual pin axis the direction of movement of the second jaw (movement axis MA), that is, it has a component of movement in a direction perpendicular to the forward-back direction of the coupler 1. It is not possible for the implement pin 2a to move into or out of engagement with the first jaw (or for the first jaw 5 to be moved into or out of engagement with an implement pin) by purely 'forward' or 'rearwards' movement that is parallel with the movement axis MA.

A locking member 19 is provided at the fixed first jaw 5. The locking member 19 is movable between a locking position shown in Figures 3, 5A and 6, in which a portion of the locking member 19 protrudes into the opening of the first jaw 5, and an unlocked position shown in Figure 5B, in which the locking member 19 is substantially or wholly retracted from the opening 11 of the first jaw 5. The first jaw 5 can be moved into engagement with an implement pin 2a with the locking member 19 in the locked or the unlocked position. In the locked position, the angled surface on the front of the locking member means that sufficient forces applied by an abutting pin 2a, push the biased locking member 19 towards its retracted position, allowing the pin 2a to enter the first jaw 5. However, in the locking position, the first locking member 19 prevents exit of an implement pin from the first jaw 5.

The locking member 19 is pivotable relative to the first jaw 5, for example, by being pivotally mounted to the first jaw 5 or the coupler body 3. In the embodiment shown the pivot of the locking member 19 is provided by a pin 21 extending between the two side plates "slide rails" 15 of the first jaw, with the first locking member 19 siting between these side plates 15. However, other configurations for the locking member are envisaged.

The locking member pivot 21 is positioned forward of the first pin seat 13 and forward of tip of the lip 17. In its locking position, the locking member extends generally downwards and rearwards from the pivot 21, towards the seat 13. The locking member pivot 21 may be directly above or forward of the mouth 11 of the first jaw 5. Preferably the position and shape of the locking member 19 is such that the locking member 19 is not ordinarily in contact with a first pin 2a when the pin is seated in the first jaw 5. Rather, during ordinary use of the coupler there will be a space between the locking surface 27 of the locking member and the pin 2a, and contact will only occur when the locking member 19 is performing a safety function, such as when there is a failure of the actuator 9.

Similarly, in some embodiments, the position and shape of the first jaw lip 17 is such that the lip 17 is not ordinarily in contact with a first pin 2a when the pin is seated in the first jaw 5. Rather, during ordinary use of the coupler there will be a space between the tip of the lip 17 and the pin 2a, and contact will only occur when the lip 17 is performing a safety function, such as when there is a failure of the actuator 9.

The locking member 19 is biased towards its locking position. That is, in the absence of any external force, the locking member will be in its locking position. A biasing member is provided to bias the locking member 19. In the embodiment shown, the biasing member comprises a leaf spring 22 with a first end of the leaf spring anchored to the coupler body and a second end anchored to the body of the locking member 19 on the portion of the locking member that extends into the jaw opening 11. The spring is bent and extends around the locking member pivot 21 on a front/lower side of the pivot such that the pivot 21 acts as a fulcrum for the leaf spring. Only a single spring is shown in the embodiment of the drawings, but alternatively there may be a plurality of springs biasing the locking member. A leaf spring is less susceptible to becoming jammed with grit or dirt compared to other spring types, so is less likely to fail or jam when the coupler 1 is used in a dusty or hostile environment. A leaf spring can also provide significantly more biasing force than a comparably sized torsion spring arranged about the pivot axis, and therefore is less susceptible to failure.

The locking member comprises a stop tab 25 for limiting rotation of the locking member 19. The stop tab 25 is provided on the opposite side of the pivot 21 to the main body 19a of the locking member 19. The stop tab 25 has a rear face 26 that is arranged to abut an opposing surface that is fixed relative to the body, when the locking member 19 is in the locking position. In the embodiment shown, the rear face 26 of the locking member 19 abuts a flat, vertical surface on the actuator 9 to define the locking position of the locking member 19. In the locking position, the rear face 26 of the stop tab 25 is vertical, but this may differ in other embodiments.

The locking member comprises one or more cam surface 23 (Figures 5A, 5B and 7) for moving the locking member 19. In the example embodiment, two cam surfaces 23 are provided on opposite sides of the pivot 21 to the main body of the locking member 19. However, in other embodiments the locking member may have a single cam surface or more than two cam surfaces.

In the embodiment shown, two locking surfaces are provided, adjacent and either side of the stop tab 25. The, or each, cam surface 23 is preferably an inclined surface facing generally rearwards and upwards when the locking member is in its locking position. The, or each, cam surface 23 is configured to interact with the movable member 35 carrying the movable jaw 7. A portion 38 of the movable member slides along a respective cam surface 23 to move the locking member 19 into or out of its locking position, as will be described in further detail below.

The first locking member 19 has a locking surface 27 on the portion of the locking member that extends into the jaw opening 11 of the first jaw when the locking member 19 is in its locking position. The locking surface 27 faces the implement pin 2a when the locking member 19 is in its locking position. When a first pin 2a is seated in the first jaw, the locking surface 27 may not contact the pin but will contact the pin if the pin moves from the seat, to prevent the pin 2a exiting from the jaw.

The locking member 19 has a locking surface 27 configured to face the pin 2a in the first jaw in the locking position. It is this locking surface 27 that the first pin will contact if the pin moves towards the mouth 11 of the first jaw when the locking member 19 is in the locking position. The locking surface 27 will hold the first pin 2a in the jaw 5. In the embodiment of Figures 1 to 10, the locking surface 27 is substantially flat or otherwise shaped to only have a single point of contact with the implement pin 2a when the locking member is in its locking position and contacting the pin 2a. When in contact with an implement pin 2a, the locking surface 27 is tangential to the cylindrical implement pin and so only contacts the pin at a single point CP (see Figure 10B).

In alternative embodiments, the locking surface 27 may be alternatively shaped in a manner that still achieves only a single point of contact with the implement pin 2a, or in a way that contacts the pin along a length of the contacting surface. For example, the locking surface 27 may be convex, or alternatively may be concave but with a radius of curvature that is notably larger than the radius of the implement pin. Alternatively, the locking surface may be hook-shaped and may closely follow the curvature of the implement pin 2a. In the embodiment illustrated in Figures 11A to E, the locking surface 127 is hooked at one side to assist with keeping the first pin 102a in the first jaw 105.

Figures 11A to HE illustrate an alternative embodiment first jaw 105 and locking member 199.

Referring to Figure HA, in this embodiment, the rear surface of the lip 117 is substantially linear and lies at an angle of about 30 degrees to the forward -rearward direction of the coupler or the forward-rear slide rail direction. In alternative embodiments, the rear surface of the lip 11 may be curved, for example concave.

The line TP illustrates the non-linear movement path that the first pin 102a needs to follow relative to the first jaw 105, to enter the jaw. The portion of the entry path TP forward of the pronounced lip 117 is straight. However, other paths are possible within the constraints created by the edge of the coupler body and the angled lead-in front of the jaw/lip 105, 117, for example, an upward angled path.

Figures HA to HE illustrate the first pin 102 a in a number of positions relative to the front jaw 105. These positions are indicated (a), (b), (c), and (d). In position (a) shown in Figures 11A and 11B, the front attachment pin is firmly seated in the front jaw seat 113, where it is positioned during normal use of the device. As described in more detail below, in some instances of failure or incorrect use of the coupler, the front attachment pin 102a may come into contact with the locking member 119 as shown by position (c) in Figure 11C. In this position, the contact face 127 of the locking member 119 is tangential to the pin 102a and the contact point is line with the pin centre and the pivot axis 121 of the locking member. This means that any loads are transmitted through the centrelines centre of the pin of the pivot pin 121 so there are few to no bending moments induced in the front locking member.

In the embodiment shown, the contact surface 127 of the locking member 119 is curved with a small lip 128. If the pin 102a acts in some manner to begin to retract the locking member 119, the lip 128 on the locking member 119 acts to push the front pin 102 back towards the seated position and point (b) illustrated in Figure 11D.

Alternative shaped contact surfaces of the locking member 119 are envisaged, for example a flat surface or a surface with no lip 128 are envisaged.

Figure 1 IE illustrates the movement of the pin 102a out of the jaw 105 after the front locking member 119 is retracted. The pin 102a can now advance to position (d) shown in Figure E, and beyond once the front locking member 119 is sufficiently retracted that it no longer prevents exit of the implement pin 102a from the front jaw 105.

Referring again to Figures 1 to 7, the movable second jaw 7 is a hook-shaped member, defining an opening 31 and a seat 33 for receiving the second implement pin 2b. The second jaw 7 opens to the rear of the coupler 1, that is, the first and second jaws 5, 7 face away from each other in opposing directions. The second jaw 7 comprises an extension portion 63, the extension portion having an extension surface that is parallel to the virtual pin axes VPA and movement axis MA. The extension portion 63 is positioned rear of the second jaw seat 33, with the surface of the extension preferably (but not necessarily) being contiguous with the surface of the seat 33. The extension portion surface has a rear edge that is positioned rear of the centreline of the second pin 2b vertical centre line VCb (Figure 3) when the pin is seated in the second jaw. The extension portion has sufficient length such that if the second jaw 7 were to move off the second pin 2b during use in the case of a loss of pressure in the actuator, the vertical centre line VCb of the pin would be over a point on the extension portion 63 to resist rotation of the implement in the case of hydraulic failure. This feature is described in more detail below.

In the embodiment shown, the rear edge of the extension surface 63 is positioned rear of the second pin 2b vertical centre line VCb but forward of the rear-most point of the pin 2b when the pin is seated in the second jaw 7. However, in alternative embodiments the extension portion 63 may be longer and may extend rearward of the second pin 2b. The surface of the extension member 63 is preferably flat but in alternative embodiments may have some concavity. The movable second jaw 7 is movable between an extended engagement position with the second jaw distal to the first jaw and in which the first and second jaws 5, 7 engage respective implement pins, and a contracted position with the second jaw proximal the first jaw. The member may be further movable to a hyper extended position where the spacing between virtual centres of the mouth of the fixed jaw 5 and the mouth of the movable jaw 7 is greater than the centre-to-centre spacing of the first and second implement pins 2a, 2b.

The movable jaw 7 is provided on a movable member 35, the movable jaw 7 being fixed to or integral with the movable member 35. The movable member 35 has two extensions 37 that extend forward from the second jaw 7, in an opposite direction to the jaw opening 31, and side ears 38 for coupling the movable member 35 to an actuator 9.

The movable member 35 is slidably mounted in the coupler 1 for rectilinear movement relative to the coupler body 3, towards and away from the fixed first jaw 5 along a movement axis MA. When the coupler 1 is aligned for engagement with the implement pins 2a, 2b, movement of the second jaw is perpendicular to the transverse implement pins 2a, 2b.

In the embodiment shown, the facing inner surfaces of the first jaw side plates 15 each comprise a linear guide channel 43 (see Figure 7). These guide channels 43 receive complementary guide features on the movable member, for example, side edges 45 of the movable member 35. As the movable member is moved forward or rearward by the actuator 9, the sides 45 of the movable member 35 slide forward and rearwards in the guide channels 43, to guide the motion of the movable second jaw 7. The guide channels 43 may comprise stops to define a limit of travel of the movable member 35, or alternatively the travel of the movable member may be determined by other constraints such as the stroke of the actuator 9.

The movable member extensions 37 are located above the first and second jaw openings 11, 31, but below the actuator 9 when the coupler is in the generally horizontal orientation shown in Figures 1 to 7. The extensions 37 are arranged to interact with the cam surfaces 23 of the locking member 19. Referring to Figures 5A and 5B, from an extended engagement position, as the movable jaw 7 moves towards the fixed jaw 5, rounded tips 38 of the movable member extensions 37 move into contact with the cam surfaces 23 of the locking member 19. Continued forward movement of the movable member 35 causes the flat under surface of each movable member extension 37 to slide over the respective cam surface 23 and pivoting the locking member 19 towards its retracted position. When the movable member 35 reaches its most forward position I the contracted jaw position, the locking member 19 is retracted and the cam surface(s) 23 are substantially horizontal, parallel or near parallel with the underside of the extensions 37, as shown in Figure 5B. When the coupler is moved from the contracted, unlocked configuration shown in Figure 5B to the extended engagement position of Figure 5a, rearward movement of the movable member 35 causes the flat under surface of each movable member extension 37 to slide back over the respective cam surface 23 until the movable member extensions 37 are out of contact with the locking member, allowing the locking member 19 to pivot towards its retracted position under the biasing force of the spring 22. The incline of the cam surface 23 is preferably such that the locking member 19 is gradually allowed to extend into its locking position rather than being abruptly released. The stop surface on the locking member 25 is preferably configured to come in to contact with the opposed surface on the coupler body just as the movable member extensions 37 are moving out of contact with the cam surfaces 23, to prevent such an abrupt release.

The actuator 9 is a linear actuator, preferably in the form of a double acting hydraulic ram. The actuator 9 is housed by the coupler body 3 between the first jaw side plates 15. One end of the actuator is fixed relative to the coupler body 3, and its other end is fixed to the movable member. In the embodiment shown, the cylinder of the hydraulic ram 9 is pinned to the first jaw side plates 15 via a pin 10. An actuator coupling pin 41 extends through the left and right side ears 39 to attach the ram of the hydraulic actuator to the movable member 35 such that extension or compression of the hydraulic actuator 9 moves the movable member 35 relative to the body.

The ram of the hydraulic cylinder 9 is biased into an extended position by way of a biasing member such as a spring 51 (visible in Figures 9A to 9D). The spring 51 to ensures the actuator 9 remains extended in the occurrence of loss of hydraulic pressure. In the embodiment shown, the spring 51 is a compression die spring that is provided internally in the actuator. The die spring is positioned at least partly in a cylindrical hollow of the cylinder rod and arranged to act between the rod and the barrel to bias the rod away from the barrel into an extended position. A central spindle preferably extends axially along the centre of the spring to prevent the spring buckling. The spindle may extend from the barrel of the cylinder and has a length about the same as or slightly shorter than the compressed length of the spring 51.

The internal die spring advantageously is sealed from environmental conditions, reducing the likelihood of dust and debris from the operating environment impacting on the operation or longevity of the spring. In contrast, external springs tend to collect debris such as sticks, stones, and dust, and take up valuable space in the smaller hitch bodies. However, in alternative embodiments an external compression spring may be provided around the barrel and/or the rod of the actuator, arranged to bias the actuator into an extended position. Operation of the coupler

Operation of the example coupler 1 shown in the drawings will now be described with reference to Figures 8A to 8E, which show the coupler attached to the end of an arm 70 of an excavator. The arm 70 includes a linkage to which the coupler 1 is attached via the mounting apertures 6. The linkage can be manipulated using a hydraulic ram, to move the linkage and thereby the coupler 1.

In a first step illustrated in Figures 8A and 8B, the coupler 1 is moved and, if necessary, rotated using the bucket linkage on the arm 71 to align the first jaw 5 with the first implement pin 2a but keeping the second jaw 7 free of the second implement pin 2b. The coupler 1 is then moved so the first jaw 5 engages the first implement pin 2a with the pin 2a seated on the seating surface 13, behind the jaw lip 17. A chamfer or angled lead-in surface 18 on the first jaw forward of the lip 17 helps to guide the first jaw 5 onto the pin 2a by creating an entrance to the first jaw that is wider than the pin diameter, gradually narrowing to the jaw opening adjacent the lip 17. An angled inner upper surface 20 rear of the lip 17 then guides the pin 2a in a different direction, towards the seat surface 13.

Relative motion between the first implement pin 2a and the first jaw 5 is non-linear as they are moved into or out of engagement because the lip 17 necessitates a change in direction of the movement. Relative motion between the first implement pin 2a and the first jaw 5 forward of lip 17 may be linear and parallel with the movement axis MA or may be at a slight angle as accommodated by the chamfer 18 at the front of the first jaw 5. However, rear of the lip 17, between the lip 17 and the seating surface 13, the movement vector changes and is nonparallel to the movement axis MA. In the embodiment shown, movement rear of the lip is at an angle of about 30 degrees to the MA, however this angle may be different in different embodiments. For example, the movement may be at an angle of between about 30 degrees and about 40 degrees, more preferably at an angle of between about 25 degrees and about 35 degrees.

In this first step, the movable member 35 may be in the retracted position (as shown), with the locking member 19 also retracted; or the movable member may be in the extended position with the locking member 19 in the locking position. If the movable member 35 is in the extended position with the locking member 19 in the locking position, moving the jaw 5 onto the first pin 2A pushes the angled front surface on the locking member, and causes the biased locking member 19 to retract to the unlocked position.

Either before coupling to the first pin 2A, or after engaging the first pin and before engaging the second pin, the second jaw 7 and movable member 35 may be moved towards the first jaw 5, to the retracted position (also shown in Figure 5B). As the movable member 35 moves towards the retracted position, the ends of the engagement portions 37 slide over the cam surface 23, pushing the cam surface downwards to rotate the first locking member 19 about its pivot 21, moving the locking member 19 upwards into the unlocked position.

Once the first pin 2a is seated in the first jaw 5 and with the movable member 35 retracted (Figure 8B), the coupler 1 is then rotated about the first pin 2a, with the second jaw still in the retracted position, until an under surface of the side plates 15 of the first jaw abut the second pin 2b and the second jaw 7 is aligned with the second pin, as shown in Figure 8C.

Referring to Figure 8D, in a next step, the actuator 9 is extended thereby moving the second jaw 7 away from the first jaw 5 and towards the second pin 2b. As the second jaw 7 moves away from the first jaw 5, the extension portions 37 of the movable member slide off the cam surface 23 of the locking member 19, allowing the locking member 19 to pivot under the biasing force from the leaf spring 22, until they are completely out of engagement with the locking member and the stopping tab 25 is abutting the stop surface 26 (Figure 5A) on the coupler body 3. The biased locking member 19 is then positioned in its engagement position.

The actuator 9 is further extended until the second jaw 7 engages the second pin 2b. The coupler 1 is in its final coupled configuration when the second pin 2b is seated on the seating surface 33 of the movable second jaw 7. With both pins 2a and 2b engaged with the coupler 1, the coupler can then be manipulated using the arm or boom 70 to which the coupler 1 is attached to rotate and lift the implement as illustrated in Figure 8E.

In order to uncouple an implement from the coupler 1, the above-described process is performed in reverse. As a first step, it is necessary for the second movable jaw to be moved out of engagement with the second implement pin 2b. To do this, the force applied to the movable member 35 by retracting the actuator 9 must be sufficient to overcome the bias from the spring 51 on actuator, and later in the stroke, to overcome the bias from the locking member 19 to retract the locking member 19. During the uncoupling process, it is expected that full hydraulic power will be available to the actuator 9. Accordingly, it will not be difficult for actuator 9 to provide the necessary force to overcome the spring bias and retract the second jaw.

Once the movable jaw 7 is disengaged from the second implement pin 2b, the coupler 1 can be rotated about the first pin 2a so the second jaw 7 is clear of the second implement pin and so that the coupler can be removed from the first pin 2a. Behaviour under incorrect coupling

During the coupling process, an operator sometimes cannot see the engagement of the second jaw 7 with the second pin 2b as it is often hidden by the implement, the excavator arm, or the bucket linkage. Therefore, the operator may not notice if the rear jaw 7 hasn't correctly engaged the second pin 2A. Figures 9A to 9C illustrate this scenario for couplers according to the present invention.

Figure 9A shows the front jaw of the coupler coupled and locked to the front pin 2A of an implement similar to the state shown in Figure 8D, however the rear jaw has not been correctly aligned with the rear pin and so movement of the movable jaw 7 towards the pin is halted when the tip pf the jaw 7 abuts the pin 2b. If an operator mistakenly thinks at this point that the second pin 2b is now seated in the second jaw and lifts the coupler, the implement may swing around the first pin 2a, as shown in Figures 9B to 9D, until the implement is hanging from the first pin as shown in Figure 9D.

In this hanging position, the lip 17 on the first jaw helps to keep the first pin 2a seated in the first jaw and preferably out of contact with the front locking member 19. Therefore, although the implement is swinging from the coupler it remains attached at the first pin and is not dropped from the coupler. In contrast, during the same scenario in prior art systems, the first pin 2a is in contact with the locking member, with forces from the momentum of the swinging implement being transmitted to the locking member. As the implement swings about the pin 2a, the rotational force from rotation of the implement is transmitted to the locking member on such prior art couplers, as a torque about the locking member pivot. The direction of that transmitted torque is in a direction acting to retract the locking member, and so if the force is sufficiently large, the locking member 19 of prior art couplers may be retracted in such a scenario, leaving the first pin free to exit the first jaw and thereby completely decoupling the implement from the coupler.

All couplers are susceptible to operator error; however, the features of the present invention work together to reduce the risk of an adverse outcome from the implement completely decoupling due to an operator error of this nature.

Behaviour under hydraulic failure

Various features of the present coupler work in tandem to prevent the first and second implement pins 2a, 2b falling out of engagement with the coupler 1 should there be a failure of the coupler such as a loss of hydraulic pressure in the actuator 9.

One worst-case failure scenario occurs when the coupler is in an upright orientation with the implement pins 2a, 2b vertically aligned as shown in Figure 10A. In this scenario, should there be a complete hydraulic pressure loss to the actuator 9, both implement pins 2a, 2b will remain coupled to the coupler.

Figure 10B illustrates the behaviour of the coupler 1 in the event of a loss of hydraulic pressure. In this vertical orientation the second jaw 7 is no longer able to resist the vertical weight of the implement, and substantially all of the vertical loading is transmitted through the first pin 2a, which drops out of its seated position but is prevented from dropping out of the first jaw 5 by the locking member 19, which remains in its locking position. The constriction in the first jaw opening 11 created by the first locking member 19 and the lip 17, together prevents the first implement pin 2a exiting the first jaw 5 and limits relative movement of the implement and coupler.

The self-weight of the movable member 35 and second jaw 7 (and potentially the weight of actuator rod and other connected components) act to urge the movable member 35 downwards relative to the coupler body 3, unseating the second pin 2b from the second jaw. However, the actuator spring 51 prevents the movable member dropping to a point where the extension 37 may interact with the locking member 19.

With the second implement pin 2b unseated, no weight force is transmitted through the movable jaw 7, and the weight force from the implement 73 acts rotationally about the first implement pin 2a. The extension portion 63 of the second jaw, which is parallel to the movement axis MA provides a reaction surface for the rotational force. Since the reaction forces RF1, RF2 are predominantly perpendicular to the movement axis MA (i.e. horizontal in the scenario shown), these reaction forces do not cause movement of the movable member 35 along the movement axis MA and instead are transferred to the coupler body 3. In the embodiment shown, the reaction force is transferred to the coupler body via the guides 45 on the movable member 35.

The lip 17 and locking member 19 together carry at least a majority, if not substantially all of the weight force of the implement. Figure 10B illustrates the reaction forces RF3, RF4 that act through the lip and the locking member 19. These reaction forces are in a radial direction of the first pin, extending through a centre point of the pin and perpendicular to the surface at the respective contact point. The reaction force provided by the locking member 19 preferably also acts through the locking member pivot point 21, or is very close to the pivot point 21. This is to prevent the reaction force exerting any significant torsional force on the locking member 19, particularly to ensure that the reaction force RF4 is not one that would tend to pivot the locking member 19 towards its retracted position. The actuator spring 51, second jaw extension 63, and front locking member 7, therefore all act together to ensure that both pins 2a, 2b are retained in the coupler 1 in the event of a hydraulic failure, for all possible orientations of the implement.

To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. For example, it will be apparent that although the first jaw 5 is described as the front jaw in the exemplary embodiment, the first jaw 5 may instead be the rear jaw and the second jaw 7 may be forward of the first jaw. In alternative embodiments to those shown, a second locking member may be provided at the movable second jaw to selectively constrict the opening 31 of the second jaw 7.

In some embodiments, it may be desirable to provide hydraulic power to the coupled implement. Provision of hydraulic power to an implement may be via separate hose connections that are manually connected, or more preferably there are a number of quick connect hydraulic couplers available in the industry that may be incorporated into the coupler 1, to allow hydraulic coupling to occur when mechanically coupling the implement.

The components of the coupler 1 may comprise any suitable material as will be apparent to a person skilled in the art. For example, the main components such as the housing body 3, the jaw plates 15, the movable member 35, and the locking member 19 preferably comprises steel. The components can be machined or cast, or a mixture of both. However, it is envisaged that some or all components may comprise alternative materials such as alternative metals or composite materials. Similarly, the hydraulic actuator arrangement can comprise any suitable materials and is adapted to be associated with pressure hose.

This invention may also be said broadly to consist in the parts, elements and features referred to or indicated in the specification of the application, individually or collectively, and any or all combinations of any two or more of said parts, elements or features, and where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.